A new study by researchers at the University of Washington found that the majority of women who use apps to track their periods were dissatisfied with the method, saying that the apps failed to accurately predict their menstrual cycles. They also reported that the apps didn’t allow them to add information that might affect their period, such as a change in birth control method, a stressful month, or hormonal changes due to fertility medications or breastfeeding. Oh – and they were annoyed that a lot of the apps were overly pink and flowery, as well.

Researchers interviewed dozens of women, as well as conducting a survey of 687 women and collecting data from 2,000 reviews of nine different period-tracking apps. Popular apps include Clue, Glow, Eve, Life, and Period Tracker, each of which focuses on something different – for example, Glow is supposed to be great for women trying to get pregnant, while Eve is geared toward the single woman who doesn’t want to get knocked up, and may have multiple sex partners.

The goal of the study was to find out how women track their periods, and which method is most effective. Besides period-tracking apps, scientists looked at the efficacy of using good old-fashioned pen and paper, paying attention to symptoms like breast tenderness and mood swings, relying on memory, or using a digital calendar.

Keeping track of your menstrual cycle is important for more than just making sure you’re not caught out somewhere without a tampon. If you’re trying to conceive, or trying not to, it’s vital to know when you’re ovulating, so you can do the deed (or not) when you’re most fertile. Plus, knowing where you are in your cycle can even clue you in to why you’re attracted to certain guys. Not to mention, the ins and outs of your cycle provide important information about your health, both for you and your doctor.

The takeaway from the study? Until technology catches up with women’s bodies, you might not want to rely solely on a period-tracking app to help you make a baby, or to predict your next period.